By Brian Hefty

Should you run soil tests on your farm this spring?  If you didn’t get tests last fall, then yes, you should.  Think about investing $50, $100, or $150 per acre in fertilizer.  Isn’t it worth $5 to $8 per acre this year to know you are properly investing your fertilizer dollars?  Without the soil test, all you are doing is guessing at your fertilizer program.

Here is what we suggest:

  1. Grid or zone it; don’t run composite tests.  All a composite test will tell you is the field average.  One way to look at that is if you apply the same fertilizer rate to the whole field you have then, in effect, overfertilized roughly half the field and underfertilized the other half.  Yes, we want you to run grid or zone samples, but if you say, “I absolutely can’t do that this year”, I would tell you to simply go to the worst spot in your field.  Drive right to that spot.  Pull 2 soil cores on each side of your vehicle (8 total), and then send them in for analysis.  Do the same thing in your best area.  Once you get those 2 results back you should be able to quickly see why the bad area is bad and why the good area is good.
  2. Use your spring tests to fertilize this spring.  Some people ask about testing now and fertilizing this fall, which you can certainly do.  However, this summer you will have crop removal, organic matter mineralization, rain which leads to leaching and/or erosion, and many other factors.  In other words, it may get you somewhat close, but your best bet is to test and then immediately fertilize.
  3. Use the free Ag PhD Soil Test app.  You can set up your fields at www.agphdsoiltest.com.  You can then use the app on your smartphone out in the field to bring you right to the gridpoints.  If you work quickly, there’s no reason you can’t sample 500 to 1000 acres per day.  The only thing you ever have to pay for is the soil testing portion if you submit samples.  If you are pulling 5-acre grids, your cost is $5.20 per acre.  Five times $5.20 is $26 per sample, which is what Midwest Labs normally changes per sample.  The good news is that you will get COMPLETE results.  I’ll bet that 80 percent or more of the soil samples I look at are missing key factors including micronutrients, salt levels, sulfur, base saturation and/or cation exchange capacity.  You have to have these or you may be misapplying your fertilizer.
  4. Use the results to adjust your fertility program dramatically if necessary.  I have looked at a lot of soil tests this winter where the phosphorus is really high – so high that I have told the farmer, “Do not apply any more phosphorus.”  Here’s my point.  Most people will adjust their fertility program up or down 10 to 20 percent.  In this case, I am suggesting a 100 percent adjustment!  If you do that, you will not only save money on fertilizer, you may actually help the availability of other nutrients if you have an excess of a nutrient like phosphorus in your soil.  I’m not saying that you should apply no fertilizer, UNLESS of course your soil test proves you don’t need it.  If you don’t need more of something, why spend the money?  You need to soil test and look at those tests to see where to cut and where you can best invest your fertilizer dollars.

Soil testing is a simple, easy process.  It is pretty inexpensive, but the data is powerful.  Quit wasting money on fertilizer you don’t need!  Learn where your fertilizer dollars are best invested, and control this data yourself!